Electric lamp socket with pin tap connecting means



July 28, 1953 c. E. GILBERT 2,647,246

ELECTRIC LAMP SOCKET WITH PIN TAP CONNECTING MEANS Filed NOV. lO, 1950IN VEN TOR. CHARLES E. GILBERT ATTORNEYS Patented July 28,. 1953 `Uil ITED STA-TES IPAIFENT IQFFI'CE ELECTRC LAMP SOCKET WITH PIN TAPCONNECTING" MEANS Application Novem-ber 10, 1950, Serial N 0. 194,985

fi'Ciairns. -.(Cl.339+99) `This invention relates to an electric socketvstructure and, in particular, to an electric socket especially adaptedfor parallel connection singly orfin large numberto a single paired wireconductor at anyfdesiredv position thereon.

:For ornamental purposes and, to some extent, for-utilitarian purposes,it is often desirable Ato have lights .arranged in long strings, themost popular use being in connection with thev ornamentalv Christmastree lights. The superiority voi the parallelconnected lights is so wellestab-u lished that their general acceptance is common. However,conventional socket arrangements are incxible in requiring that thewires be cut and stripped before lbeing brought into a socket,A andscrew connections must thereupon be made to connect the wires to thesocket. On the other .,hand, in most situations calling for the use ofstrings of lights, especially where ornamentation is. desired, .it willusually be desirable tohave arl rangements whereby the. stringing may bemade exible `with respect to the intervals between lights ornumber oflig ts along a string.

:Accordingly it is a fundamental object of the nstantinvention toprovide a socket .structure whichrnay be assembled on a conductordirectly `without stripping insulation so that the socket maybe placedatany point on the conductor and removed when its use is to bediscontinued.

'It is asecond object of the invention to provide a simple two-piecesocket structure having provisionfor .thepassage of electric cordtherethrough and for making electric contact with the cord di y `rectl-ywithout the employment of tools for stripping insulation or connectingwire to the socket. It is a third object of the invention to provide .asimple 'two-piece socket structure for usewith conventional electriccord which wiil Apermit mounting of a plurality of the sockets at anyintervals desired-on an electric cord to provide for any desiredarrangement of lamps thereon.

Other objects and advantages of the invention will in part be obviousand in part appear hereinafter..

"The invention accordingly is embodied in la socket structure lformed4of essentially two pieces, the one carrying the electrical contacts andthe othermating piece providing for forcing electric cordlinto Contacttherewith, the two elements being formed for sliding engagement witheach other-to complete a unitary two-piece structure having the features.of construction, .combinations of. elements, and arrangement of partsherein after to be described in greater detail.

In .the dratvingsillustrating a preferred embodiment ofthe invention:

Figure `1 constitutes a longitudinal lsection vthrough the socket in`the plane of Vthe electric .cord conductor. passingv therethrough,`showing a bulbin place in the lsocket making contact with the electricalsocket contacts thercinand further showing the electricy connection Yofthose contacts to the cord;

, Figure 2..is.a longitudinal scctionthrcugh the socket -talenat rightangles to the view shown in Figure 1;

Figure 3 is a bottom View of the body portion which receives the lightbulb;

Figure Ilis a top .plan View of the body portion shown in'Figure' 3;

Figure 5 is a plan View of the cap or cover element cooperating with thebody portion shown in Figures 3 and 4;

,. Figure 6 is an end view ofthe cover element shown inFigure `5;

Figurev is an opposite end view of the cover elements;

*Figure A8 is a side elevation of the body portion;

Figure 9 is a second'side elevation of the body portion taken at rightangles to the'view shown nli'gure '1;

.Figure 10 is a planvlew of one or" the electrical contacts formeoliorassembly with the'sccket bodyportion; and.

l"Figure l1 is a similar side elevation of the other electrical Contactformed y:forassenfibly with the socket body portion.

. IReferring back to Figure 1 showing a section through an assembledunit-mounting' an'electric light bulb, .It represents a bulb ofsubstantially conventonaliorm having usual metal screw base il, in whichthe threaded. portion serves as one contact, and the' insultaing cap l2having a .conductive tip 1,3. forming a second contact to .complete the,circuit throughthe bulb iilament.

'The sooketbody lil which receives the bulb is prefat- `respectivegrooves vbetweenthe threaded lportion l5, contact .lbeing `formed with.an offset central portion 2| to meet and .make ,electric-al conta-ctwith vthe threaded vbase ofthe bulb and lcontact ll @formed withacentral portion 20 thereof bent inwardly, substantially to the 3 centerof the cylindrical socket to make contact with the conductive tip of thebulb. The two conductive elements I6 and Il have sharpened tips I8 andI9, shown in more detail in Figures 9 and 10, which extend downward intochannel 29 to form electrical contact with the wires of a cord passingthrough the socket structure, as will be shown in greater detail.

In Figures l and 9, contact Il is shown to be essentially a rectangularelectrically conductive piece in which a central tongue 23 is cut out.To make contact with the tip I3 of the bulb base, the tongue 2D is bentoutward perpendicular to the piece to the center of the cylindrical bodyopening, as shown in Figure 1.` The bottom of the piece has a pair ofsharp prongs I9 formed thereon and aligned to be offset to one side ofthe center of the base.

In Figure l0, contact l5 is shown as essentally a rectangularelectrically conductive piece in which a central tongue 2I is cut out.To make contact with the bulb base II, the tongue 2l is bent forwardtoward the center suciently to meet the threads of the bulb base. Likeelement I9, the bottom of contact l'I has a pair of sharp Y prongs I8formed thereon and aligned to be offset on the opposite side of centerfrom prongs I9.

Socket body I4 is formed, preferably by molding, to have twosymmetrically placed longitudinal grooves recessed therein and havingse'ctions such that contacts i6 and Il may be slipped thereinto from thebottom, as shown in Figure 3, to be retained in the grooves by a pressedor frictional fit.

Referring to Figure 2, which is essentially a section taken at rightangles to that shown in Figure l, the several parts of the socket may bereadily identified. Socket body i4 is of fundamentally cylindrical formand terminates at the lower end of the cylinder in outwardly extendinglongitudinal projections 25 and 2E so that the outline of the socketbody resembles a T. Extending parallel to the longitudinal projections25, 2E is a cord-receiving channel 29 formed centrally in the lower partof the body i4, as shown most clearly in Figure 8. It will be understoodthat the prongs I8 and I9 of contact elements I6 and I'I extend intochannel 29, as shown in Figures 1 and 2, with the prongs I8 near oneside of the channel 29 and the prongs I9- near the other side. Matchingcap 28, which completes the unit, has an internal outline matching theexternal T configuration of the socket body to form a sliding i'lt withthe body of the socket to cover channel 29. As will be described, thiscap or cover 28 presses against the cord 21 in channel E9 to force thecord against the prongs I9 and i9, so that these prongs pierce the cordinsulation and make electrical contact with the respective wires of thecord.

In Figure 7 the side elevation of socket lll indicates it may haveportions thereof offset or tapered for ornamental purposes but willgenerally have two opposite planar faces 4I and 42 paralleling theprojections 25 and 29 so as to provide for receiving the sliding cap 28.Figure 8 shows the socket element in the direction at right angles tothat of Figure '7.

The structure of the cap 28 to form the sliding fit on the base of thesocket body to compress the cord against the sharp projecting prongs ofY socket body. The cap 28 is also formed with an outwardly extendingflange 39 on one side to identify the slightly widened end thereof whichpermits easy entry on the T-shaped base of the socket. The upwardly 'andinwardly extending sides 3| of the `cap denne a channel in which theT-'shaped section of the socket body base lits.

In Figure 6, which is a view taken from the narrower end of the baseplate, the flange 39 at the back thereof is identified and the extremesof the opening 32 for receiving the projections 25, 26 of the socketbody base are shown in dotted lines. The opening quickly tapers to aclose lit for the body base. The several projections appearing on theinner face of the channel have their purposes as follows: the twocentral projections 33 and 34 are, respectively, on either side of theaxis of channel 29 in alignment with the sharp prongs I8 and I9 formingthe parts of the electrical contact members, so that when the device isassembled, these projections will compress the cord in groove 29 againstthe prongs. thereby establishing electrical contact with the encasedwire. For this purpose, these projections 33, 34 are wedge-shaped inlongitudinal section, and merge into the main portion of cap 28. The twoprojections 35 and 36 are oriented at the narrower end of the base plateand serve simply as stops for engaging the base of the socket body andstopping it when it is substantially centrally located over the baseplate.

From the above description of the struc ture of the parts, the functionand the manner of assembly of the socket should be readily understood.Briefly, in the assembly of the socket and establishment of electricalcontact with wires encased in insulating material, such as conventionalrubber covered lamp cord, the wire or lamp cord is laid in the groove 29of the socket (conventional two-wire rubber covered lamp cord would beused for the assembly of ornamental Christmas tree lights), and cap orcover 28 is tted over the end of the body base and slid into place untilit engages stops 35 and 36. In being forced into position, projections33 and 34 on the plate serve to compress the wire against the prongs I8and I9 of wire 2l sunciently to cause the prongs to pierce the softinsulating covering of the wire and establish electrical contact withthe encased wires substantially yas shown in Figures 1 and 2. In thismanner one or any number of sockets may be assembled on a wire, up tothe current carrying capacity of the wire.

It will be understood that any suitable type of cord may be used,although parallel conductor cords are preferred. If desired, separatesingle wires may be used. In any case, the wedge projections 33, 34 ofthe cap 28 are proportioned to force the wires of the cord into contactwith the prongs I8, I9, whereby the wires are electrically connected tothe Contact elements I6, Il and thence to the terminals of the lightbulb.

It will be understood that the socket described above may be used in anyposition, and may have the light bulb extending downwardly or at anydesired angle.

Thus there has been described an extremely simple bulb socket, made of aminimum number of easily fabricated parts and adapted for assembly bythe user without any tools whatever, which permits mounting of one ormore light bulb sockets on a cord at any desired locations therealongThough the invention has been described in connection with only a singleembodiment thereof, the fundamental principle should be apparent andvariations thereof without departing from the spirit or scope of theinvention may readily be made.

What I claim is:

1. A socket for electric light bulbs having a threaded base terminal anda further central tip terminal, comprising a hollow unitary body ofinsulating material having a substantially cylindrical bore, a pair ofgrooved recesses formed in the inner surface of said bore diametricallyopposite one another and extending partially therealong from one endthereof to form respective shoulders, said bore having threads formedtherein adapted to receive the threaded base of a light bulb, a pair ofiiat electrical contact elements integrally formed of sheet metal havingportions respectively slidably seated in said recesses in abutment withsaid shoulders and having projections integrally formed therewith andadapted to make electrical contact with the respective terminals of saidlight bulb when inserted in said threads, said hollow body having achannel formed transversely at said one end of said bore and extendingin lalignment with and communieating with said recesses, each of saidcontact elements being provided with an integral pointed end formed atone end of said rst named portions and extending into said channel forpiercing the insulation of a respective one of the insulated wires of anelectrical conductor cord when lying in sai-d channel to make electricalcontact with said wires, said body having a pair of ridges extendingalong the outer walls thereof parallel to and in part coplanar with saidchannel, and means in the form of a cover having linearly extendingreentrant edges slidably engaging said ridges for covering said channel,said cover having an inner surface substantially parallel to the base ofsaid channel and a pair of projections at locations respectivelyopposite said pointed contact ends for holding such an electricalconductor cord in contact with said contact element ends.

2. A socket for electric light bulbs comprising a hollow unitaryinsulating body having a transverse channel at one end thereof and apair of grooved recesses extending from said channel longitudinally ofsaid body and terminating in respective shoulders, said body having a,substantially cylindrical longitudinal bore between said recesses andbeing formed with threads on the inner surface of said bore for engagingthe threaded base of 'a light bulb, a pair of electrical contactelements extending in said recesses with one end abutting a respectiveone of said shoul-` ders and each having a pointed end thereof withinsaid channel for piercing the insulation of an insulated wire, each ofsaid contact elements being formed of sheet material and also havingmeans formed integrally therewith for making electrical contact with arespective terminal of a light bulb when engaging said threads, saidbody having a pair of flanges extending along the cuter walls thereofparallel to said channel, and means including an integral cover havinglongitudinally extending re-entrant portions slidably engaging saidflanges for covering said channel and having an inner surfacesubstantially parallel to the base of said channel and a pair ofprojections on said inner surface at locations respectively oppositesaid pointed contact ends for applying pressure to an electricalconductor cord when placed in said channel to press the respective wiresof said cord into contact with the pointed ends of said electricalcontact elements to make electrical contact between each of the wires ofsaid cord and a respective contact element.

3. A socket as in claim 2 wherein said cover has a pair of furtherprojections extending from the inner surface adjacent one end adapted toengage said body to define a position for said cover at which said firstprojections are opposite said contact pointed ends.

4. A socket for electric light bulbs having a threaded base shellforming one termin-al thereof and a further tip terminal, :comprising anintegral molded hollow insulating body having a substantiallycylindrical bore, a pair of grooved longitudinal recesses formed indiametrically opposite portions of said bore and extending partiallytherealong to terminate at one end in respective shoulders, a channelextending across one end of said body transversely thereof and joiningthe other ends of said recesses, a p-air of unitary stamped sheet-metalcontact elements mounted respectively in said recesses in abutment withrespective shoulders, one of said elements having a bent-out integralprojection extending into said cylindrical bore and adapted to makeelectrical contact with the threaded shell terminal of a light bulb wheninserted into said bore, the other of said contact elements having abent-out integral projection extending inwardly of said boresubstantially to the center thereof for making electrical contact withthe tip terminal of such a light bulb, -each of said contact elementsfurther having a sharp pointed end extending into said channel adjacentrespective opposite sides thereof, said body further having a pair offlanges extending transversely thereof adjacent to and parallel to theedges of said channel, and a sliding cover adapted to cover said channeland having reentrant lips engaging said flanges for retaining said coverin engagement with said body, said cover having an inner surfacesubstantially parallel to the base of said channel and protuberances onits inner surface in register with said channel whereby when a conductorcord is laid in said channel and said cover is slid over said body andcord. said protuberances are adapted to force said conductor into acontact with said Icontact element pointed ends whereby said ends piercethe insulation of said conductor cord and make electrical contactbetween the respective wires of said cord f and the respective lightbulb terminal-engaging portions of said contact elements.

CHARLES E. GILBERT.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,820,261 White Aug. 25, 1931 2,353,778 Mattis July 18, 19442,465,700 Tuttle Mar. 29, 1949 FOREIGN PATENTS Number Country Date390,294 Great Britain Nov. 30, 1932

